Safety device for elevators



(No Model.) 2 Sheets-Sheet 1. G. 0. HOWARD.

SAFETY DEVICE FOR ELEVATORS.

No. 519,844. Patented May 15,1894.

1 iiiii Iflluli'llllJ (No Model.) 2 Sheets-Sheet 2.

G. G. HOWARD. SAFETY DEVICE FOR ELEVATORS.

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Patented May 15, 1894.1

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UNITED STATES PATENT OFFICE.

GEORGE C. I-IOIVARD, OF PHILADELPHIA, PENNSYLVANIA.

SAFETY DEVICE FOR ELEVATORS.

SPECIFICATION forming part of Letters Patent No. 519,844, dated May 15, 1894.

1 Application filed December 4, l 893. Serial No.'492,748. (No model.)

To 00% whom it may concern.-

Be it known that I, GEORGE C. HOWARD, of Philadelphia, county of Philadelphia, and State of Pennsylvania, have invented a new and useful Improvement in Safety Devices for Elevators, of which the following is a specification. I

My invention relates to a safety catch or brake for elevators, and it consists broadly in combining with a brake carried by the elevator and normally held out of action by the force of gravity, an operating mechanism acting constantly on the brake in opposition to the force of gravity and constructed to overcome the same when the elevator reaches an undue or abnormal speed, and to throw the brake into action and arrest the motion of the elevator.

In applying my invention I prefer to connect to the elevator movable brake shoes in position to engage the vertical guides between which the elevator moves, the brakes being arranged to be held out of engagement with the guides by the force of gravity, and I combine with these brakes an actuating mechanism constructed to exert a constant force ity, it will operate the brakes and throw them into contact with the guides and arrest the motion of the elevator.

The brakes acting in the manner above set forth, may be of various forms and constructions, and the actuating mechanism for the same may be controlled by springs, hydraulic or other pressure, magnets, and by other means, as will be more fully described hereinafter and illustrated, and my invention is designed to comprehend all and any of these means, provided the operation of the parts will be substantially as described above.

In the accompanying drawings, Figure 1 represents a side view of an elevator provided with my invention in its preferred form. Fig. 2 is a horizontal section through the same on the line 2-2. Fig. 3 is .a bottom plan view of the same. Fig. 3 is a section showing the actuating spring applied to an arm projecting from a shaft connecting the brakes. Fig. 4 is a side elevation of an elevator and brake showing an actuating mechanism for the brake controlled by fluid pressure. Fig. 5 is a similar view showing the actuating mechanism controlled by a magnet. Figs. 6 and 7 are side elevations and top plan views respectively of an elevator showing my invention applied, the brakes being in a modi- -fied form. Figs. 8 and 9 are a side elevation and top plan view respectively of still an other modified form of brake.

Referring to Figs. 1, 2 and 3, 1, represents an elevator car provided atits sides with Gel guide shoes 2, which embrace and move on vertical guides 3, to guide and steady the elevator car in its ascending and descending movements as usual. The shoes 2 comprise castings formed as represented in Fig.3, with vertical guideways 4, in their outer sides to receive the vertical guides 3 and with horizontal flanges 5, on their inner sides by which they are bolted to the bottom of the elevator, the construction and arrangement thus far being the same as usual in elevators. To each guide shoe at the side of the vertical guideway is pivoted abrake block 6, arranged to swing in a vertical plane and in the adjacent wall of the guideway is an opening through which the free end of the brake block is adapted to swing into engagement with the vertical guide. At the sides opposite the brake blocks, the shoes are provided with bearings 7, in which are journaled the ends of a shaft 8, extending transversely beneath the bottom of the elevator. This shaftis provided near its ends with crank arms 9, which are coupled by means of toggle links 10, with the respective brake blocks. Thus by rocking the shaft the brake blocks can be lifted into or lowered out of engagement with the vertical guides. y

The brake blocks are held normally out of action by the force of gravity and are automatically lifted into engagement with the guides when the elevator travels at an undue mounted on the elevator and the connecting speed, by means of springs 11, one at each side of the elevator. Each spring has one end connected with the elevator and its opposite end to the brake blocks. They exert a constant lifting force on the brake blocks in opposition to the force of gravity, and the brake blocks are of such weight relatively to the force of the springs, that as the elevator is descending at a normal working speed, the force of the springs will be overcome by that of gravity, andthe brake blocks will be held out of action. When, however, from any cause, such for instance as the breaking of the hoisting rope, the elevator descends at a dangerous abnormal speed, the force with which the brake blocks press upon the sustaining springs under the action of gravity is neutralized, the springs being then permitted to expand and throw the brakes into action.

While the elevator is 'at rest, the springs sustain the full weight of the brake blocks and are then more or less compressed, according to their strength and the weight of the blocks. When the elevator begins to descend, the equilibrium is destroyed and the force with which the brakes bear down on the springs is diminished, the diminution being in proportion to the velocity of movement. This diminution of pressure is not sufficient to produce any material effect during ordinary or safe rates of speed, but at unusual rates of speed it is sufficient to permit an expansion of the springs and to produce thereby a movement of the brake blocks, relatively to their point of support in the'guide-shoes, to throw them into action.

The springs to move the brake blocks may be applied in various ways, and in Fig. 1 I have represented in dotted lines and in Fig. 2, in full lines, a coiled torsional spring 12, encircling the horizontal shaft, with one end connected to the shaft, and its opposite end fixed to the elevator.

In Fig. 3 I have represented a coiled expansion spring 13, bearing at its opposite ends on the under side of the elevator, and against the outer end of an arm 14:, fixed to the shaft.

Manifestly various forms of springs may be used and applied in various ways, these being matters which fall entirely within the province of the mechanic, it being only necessary that the spring in any form be so applied as to exert a constant force on the brakes in opposition to that of gravity.

The brake blocks may be independently shaft may be entirely omitted, the office of the latter being to connect the brake blocks, when two are employed, to cause them to operate simultaneously.

In Fig. 4: I have represented a modified form of actuating mechanism for the brake block. In this case the force acting on the brake block in opposition to that of gravity, is exerted by hydraulic pressure, the end of the brake block being pivoted to a piston rod 15,

which is fixed to a piston 16, moving in a vertical cylinder 17, fixed to the elevator. The cylinder is in communication by a pipe 18, with a source of water or other fluid under pressure.

In Fig. 5 the actuating mechanism is in the form of a magnet 19, the brake block constituting the armature of the magnet. The magnet may be a permanent one, or an electro magnet may be used, in which case the current will be supplied through circuit wires 20, extending to a source of electric energy.

In Figs. 0 and 71 have represented a modifled form of brake. In this casethe brake is in the form of a wedge 21, carried by the end of a lever 22, pivoted tothe elevator. The wedge is adapted to be forced by the actuating mechanism between an inclined guide carried by the elevator, and the side of the vertical guide 3. The mechanism for actuating the brakes in this instance can be controlled by a spring, by fluid pressure or by a magnet, as in the cases heretofore described. In place of the Wedge 21, a roller 24 may be applied to the end of the lever, as shown in dotted lines.

In Figs. 8 and 9 the brake is in the form of astirrup 25 mounted at one end in a bearing 26, carried by the elevator and embracing the vertical guide 3. The inner edges of this stirrup are sharpened or pointed so as to act with a grip on the guides when it is thrown into action. The stirrup like the brakes already described may be acted on by springs, fluid pressure or magnets or by other means.

In all the cases above described it will be seen that the brake is carried by the elevator, is held normally out of action by gravity, and is acted on by a mechanism which exerts a constant force in opposition to the force of gravity, the relative strength of the actuating force and the weight of the brakes being such that when the elevator exceeds a predetermined speed in its descent, the force of gravity is overcome by the actuating mechanism, and the brakes are thrown into action and the motion of the elevator is arrested.

As before stated, While either springs, magnets or fluid under pressure may be employed to actuate the modified forms of brakes represented in Figs. 6, 7, 8 and 9 for the purposes of illustration I have shown coiled springs 27 for this purpose, the said springs being connected at their ends to the car and brakes, like in Fig. 1.

Having thus described my invention, what I claim is 1. The combination with an elevator of a brake carried thereby and arranged to be held out of action by gravity and an actuating mechanism also carried by the elevator and acting constantly on the brake in opposition to the force of gravity.

2. The combination with the elevatorof the vertical guides, the vertically moving brake carried by the elevator and arranged to engage the guide and held out of action by the brake into action when the elevator exceeds a predetermined speed.

4. The combination with the elevator, the guide and guide shoe, of a friction brake mounted in said shoe to swing in a vertical plane into and out of engagement with the guide, and held normally out of action by the force of gravity, the transverse crank shaft journaled in bearings in the elevator and connected with the brake, and a spring applied to the shaft to throw the same against the weight of the brake.

5. The combination with the elevator, the vertical guides therefor and the guide shoes, of the friction brakes mounted in said guide shoes to swing in a vertical plane into and out of engagement with the guides, the transverse crank shaft mounted in bearings beneath the elevator and having its cranks coupled to the brake, an arm projecting from said shaft, and a spring bearing at its ends against the bottom of the elevator and the arm on the shaft.

In testimony whereof I hereunto set my hand, this 9th day of October, 1893, in the presence of two attesting witnesses.

GEORGE G. HOWARD.

Witnesses:

PAUL W. KNAUF, E. E. LAUDENSLAGER. 

